Process for the pasteurization of egg whites

ABSTRACT

A PROCESS OF PASTEURIZING EGG WHITES WHICH CONSISTS OF DISSOLVING WITHIN SAID EGG WHITES A FOOD GRADE ALKALI POLYPHOSPHATE MATERIAL IN AN AMOUNT RANGING BETWEEN 0.20 AND 2.0% WEIGHT. THE PH OF THE EGG WHITES IS THEN ADJUSTED TO A RANGE OF BETWEEN ABOUT 8.0 AND 10.0. THE EGG WHITES ARE THEN HEATED TO A PASTEURIZATION TEMPERATURE FOR A SUFFICIENT LENGTH OF TIME TO PASTEURIZE THE EGG WHITES.

United States Patent 3,737,330 PROCESS FOR THE PASTEURIZATION OF EGGWHITES Willibald F. Kohl, Nanuet, and John C. Sourby, Mount Kisco, N.Y.,and Rudolph H. Ellinger, Chagrin Falls, Ohio, assignors to StaulferChemical Company, New York, N-Y.

No Drawing. Continuation-impart of application Ser. No. 694,797, Jan. 2,1968. This application June 8, 1970, Ser. No. 44,605

The portion of the term of the patent subsequent to July 14, 1987, hasbeen disclaimed Int. Cl. A23b /00 US. Cl. 99-215 8 Claims ABSTRACT OFTHE DISCLOSURE A process of pasteurizing egg whites which consists ofdissolving within said egg whites a food grade alkali polyphosphatematerial in an amount ranging between 0.20 and 2.0% weight. The pH ofthe egg whites is then adjusted to a range of between about 8.0 and10.0. The egg whites are then heated to a pasteurization temperature fora sufiicient length of time to pasteurize the egg whites.

RELATED APPLICATION This case is a continuation-impart of applicantscopending case S.N. 694,797, filed Jan. 2, 1968, and now.

Pat. No. 3,520,700.

BAOKGR'OUND OF THE INVENTION There are a number of food poisoningmicro-organisms that cause serious problems in the food industry. Amongthese different spoilage organisms which may contaminate foodstuff, thegroup Salmonellae have gained special importance. Salmonellae arepathogenic gram-negative rodlike bacteria that have drawn much recentattention that is well documented in the literature. Of the several foodareas involved, particular interest has been generated in the reductionof Salmonellae in egg products. The contents of an egg with unbrokenshell may already contain bacteria caused by the infection of a layinghen. The exterior surface of the egg may be contaminated with bacteriafrom the intestinal tract of the hen, from the nest or from othermaterial contacted after laying. Some of these can be introduced intoegg products during breaking operations. Bacteria can also penetrate theshell from outside. The invading microorganisms infect the egg and canbe carried on into a variety of egg products.

The elimination of Salmonellae by pasteurization of egg products hasbecome mandatory under United States Department of Agricultureregulations. According to these regulations all egg products have to bepasteurized regardless of whether they are to be distributed in frozen,liquid or dried form.

There are problems in pasteurization that are peculiar to egg whites ascompared to whole eggs or yolks. All pasteurization processes for eggwhites must be a com promise between the amounts of heat applied to killSalmonellae and the coagulation of the egg proteins, which affect thefunctional properties thereof. Although naturally occurring levels ofSalmonellae are seldom greater than 100 per milliliter of egg product,present processes have need of improvement to minimize undesirableeffects on functional properties or excessive buildup on plantequipment. Present processes also lack retained inhibitory effects afterpasteurization.

At present, there exist several processes which give acceptabledestruction of Salmonellae in egg Whites. One of these processes isdescribed and claimed in US. Patent No. 3,251,697, which involves theaddition of a food grade acid to lower the pH of the egg whites fromabout 9.0 to about 7.0, and with the addition of aluminum or other metalions to stabilize the egg proteins against coagulation at highertemperatures. These materials may be added to give a concentration of 30parts per million as aluminum, added in the form of aluminum sulfate and0.15% lactic acid in the egg whites. The egg whites may then bepasteurized at a temperature of 140 to 143 F., at a holding time of 3.5minutes. This procedure is reported to destroy one million addedSalmonellae per milliliter. However, it has been found in practice thatthe bacterial count in this process is relatively high after treatment.Also, the aluminum sulfate in the egg whites will cause the appearanceof small particles of precipitated egg proteins.

Another proposed solution to killing the bacteria with in the egg Whitesis described and claimed in US. Patent No. 2,776,214. This processinvolves taking the egg white at its normal pH, heating it to to 130 F.for a period of 0.5 to 5 minutes. This is claimed to largely inactivatethe indigenous catalase. Thereafter, sufiicient hydrogen peroxidesolution is metered in to give a concentration of 0.1% peroxide in theegg whites. The egg whites are then reheated and then they are cooledand catalase is added to destroy the residual peroxide. This process isreported to produce sterile egg white. This process has a seriousdrawback because a relatively high amount of bacteria may survive thepasteurization process when heat resistant bacteria strains are presentin the egg whites.

BRIEF DESCRIPTION OF THE INVENTION It has been discovered that theSalmonellae within egg whites can be materially reduced by treating theegg whites with a synergistic combination of polyphosphate and an alkalidonating material to adjust the pH of the natural egg whites to between8.0 and 10.0. Thereafter, the egg whites are pasteurized at atemperature of between about and less than F., depending on the pH ofthe egg whites, for a period of from 0.5 to 10 minutes holding time.

DETAILED DESCRIPTION OF THE INVENTION In the practice of the presentinvention, the liquid egg whites are separated from the yolks in aconventional manner. Thereafter, an alkali containing polyphosphate isadded thereto in an amount ranging from 0.20 to about 2.0 percent byweight. The alkali containing polyphosphates can be represented by theformula (NaPO where n can range between 3 to 40.

The polyphosphates represented by this formula can be linear or cyclicand can be coupled to H O or Na O'. Specific examples of a polyphosphatethat can be employed with the present invention can include sodiumhexametaphosphate, sodium tetrapolyphosphate, sodium tripolyphosphate,sodium hexapolyphosphate, sodium heptapolyphosphate, sodiumoctapolyphosphate and the like.

After the polyphosphate material has been dissolved within the eggwhites, an alkaline containing material is added thereto to adjust thepH to between 8.0 and 10.0, preferably between 8.5 and 9.7. The alkalinecontaining material may be selected from the group consisting of sodiumhydroxide, potassium hydroxide, ammonium hydroxide, sodium phosphate,calcium hydroxide, sodium carbonate, and the like.

When the pH of the material has been determined to be between 8.5 and10.0, the egg whites are then pasteurized at a temperature of betweenabout 110 and less than 125 F. The exact temperature of pasteurizationof course will depend on the pH of the egg whites. It has been found inpractice that the holding time of the egg whites during pasteurizationshould be from 0.5 to minutes. After the egg whites have beenpasteurized, they are cooled. The pH is adjusted to the original leveland then they are placed in storage in a conventional manner.

In the practice of the present invention, it has been found that thecombination of polyphosphate materials with the alkaline containingmaterial provides considerable residual killing power for bacteria.Thus, on aging, the egg whites as processed by the present inventionwill be provided with much fewer bacteria than the conventionallyprocessed egg whites.

It has also been discovered that egg whites can be effectivelypasteurized in accordance with the process of this invention attemperatures between about 110 F. and less than 125 F. Experimentalexamples described in our copending application of which this is acontinuationin-part appeared to indicate that the range of operabilitywere then pasteurized at 'a temperature of 130 F. for

five minutes holding time. An assay of the egg whites using standardmicrobiological procedures showed thesamples to be Salmonellae negative.

Example '6 Eggs were broken by hand, egg whites were obtained in thesame manner as in Example 1. Microbiological cultures of Salmonelladerby, Salmonella organienburg, and Salmonella typhimurium' which hadbeen grown in egg whites a stheir growth medium, were mixed into 4liters of fresh egg whites, to give a concentration of 1.3 millionSalmonellae per ml. of egg white. An amount of 40 ml. of

might be limited to 125 F. to 135 Examples 7 and 8 which are presentedherein below demonstrate operability within the temperature rangebetween abut 110 F. and less than 125 F.

Example 1 Egg whites were obtained from fresh eggs by separation thereoffrom the yolks and mixed to form a uniform batch. Then, a bacterialculture of Salmonellae senftenberg 775W was added to provide aconcentration thereof of 7.2 millions per milliliter. Thereafter, 0.75%by weight of sodium hexametaphosphate was dissolved therein. The pH ofthe egg whites was raised to 9.4 by employing an alkaline agent,trisodium orthophosphate. The egg whites were then subjected to apasteurization temperature of 135 F. for five minutes holding time. Theegg whites were then cooled to 38 F. The egg whites were then assayedfor surviving Salmonellae using standard microbiological procedures. Itwas determined that the samples were Salmonellae negative.

Example 2 The procedure of Example 1 was repeated in its entirety exceptno sodium hexametaphosphate or trisodium orthophosphates were addedthereto. Under these conditions, without additives, the average numberof surviving Salmonellae was assayed to be 12,000 per milliliter.

Example 3 for Salmonellae by standard microbiological procedures.

The assay showed the samples to be Salmonellae negative.

Example 4 The procedure as set forth in Example 3 was repeated in itsentirety except no sodium polyphosphate or sodium hydroxide was addedthereto. After the pasteurization procedure as outlined in Example 3 wascompleted, an assay of the egg whites indicated a survival of 1160Salmonellae per milliliter within the egg whites.

Example 5 Egg whites were obtained in a manner as set forth inExample 1. A bacterial culture of Salmonellae typhimurium was addedthereto to provide a concentration thereof of 2.4 millions permilliliter. Then, 0.5 by weight sodium hexametaphosphate was dissolvedtherein. Thereafter, a 10% solution of sodium hydroxide was added toraise the pH of the egg whites to 9.5. The egg whites a neutral aqueoussolution of 50% sodium hexametaphosphate was added under stirring to 4liters of Salmonellae containing egg whites. The alkalinity of the eggwhites was then raised through drop-wise addition of an aqueous 10%solution of sodium hydroxide to a pH value of 9.9. The egg whites werepasteurized in a laboratory pasteurization apparatus at 121 F. for 3.5minutes holding time. The egg whites were cooled after pasteurizationand were tested for surviving Salmonellae by standard microbiologicalpro cedures. The Salmonellae tests were negative.

Example 7 The procedure as set forth in Example 10 was repeated in itsentirety except that the pasteurization temperature was 116 F. From theinitially present 1.3 million per milliliter Salmonellae less than 500per milliliter survived the treatment, indicating a kill in excess of99.9%.

Example 8 Egg whites were obtained from fresh eggs in a commercialcontinuous operation. The egg whites were assayed for their totalbacterial flora count by using standard microbiological procedures. Theconcentration thereof was 16,500 per milliliter. To a portion of theseegg whites was added 0.5% by weight sodium hexametaphosphate followed bydropwise addition of a 10% solution of sodium hydroxide to raise the pHof the egg whites to 9.5. The egg whites with these additives werepasteurized at a temperature of 130 F. for five minutes holding time.The pasteurized egg whites contained an average of 500 bacteria floraper milliliter. However, the samples were Salmonellae negative. Thepasteurized eggs were kept at 77 F. room temperature, for three days.The total bacterial flora count was checked daily. It was found that thebacterial flora count decreased gradually. The

average number of bacterial flora were 330 per milliliter after one day,270 per milliliter after two days, and per milliliter after three days.These results show a lasting inhibitory effect upon bacterial flora inegg whites after pasteurization. It is apparent that the combination of0.5% sodium hexametaphosphate plus an alkali to raise the pH to 9.5causes the total bacteria flora count of the egg whites to decreasematerially during pasteurization and causes the residual bacterial florato diminish with storage at room temperature.

1 Example 9 A standard stabilizer solution, composed of aluminum sulfateand lactic acid, was added to the removing egg white of Example 6 in anamount of 0.6% by weight. The egg whites were then pasteurized at 142 F.for 3.5 minutes. An assay of the egg whites after pasteurizationemploying standard microbiological procedures indicated 2500 bacterialflora per milliliter survived from the 16,500 per milliliter initiallypresent. After standing at room temperature, the number of bacterialflora increased.

Example 10 Egg whites were obtained from a commercial continuousbreaking operation. An assay of the egg whites indicated the presence of16,500 bacterial flora per milliliter. The egg whites were thenseparated into six equal portions. The following additives were added toeach portion:

(1) 0.5% sodium hexametaphosphate plus a solution of sodium hydroxide togive a pH of 9.5;

(2) 1.0% sodium hexametaphosphate plus a 10% sodium hydroxide solutionto give a pH of 9.5;

(3) a 10% solution of sodium hydroxide alone to give a pH of 9.5;

(4) 0.1% hydrogen peroxide followed by addition of catalase after tenminutes;

(5) 0.6% stabilizer solution consisting of aluminum sulfater dissolvedin lactic acid, to provide a pH in the egg whites of 7.0;

(6) no additives added. The pH determined to be 8.9.

The effectiveness of the additives in the egg whites toward the naturalbacterial flora was tested. The egg whites were stored at C. for threedays. In daily intervals the standard bacterial plate count wasdetermined. The results of these plate counts are tabulated as follows:

STANDARD BACTERIAL COUNT [per 1111.]

Initial bacterial After 24 After 48 After 72 count in hours at hourshours at Number egg whites 25 C. 2 C. 25 1. X10 2.1)(10 8. 6X10 9. 4x101 65X10 1.6)(10 8.1X10 6.0X10 1 65X10 3.1)(10 1.4)(10 4 2X10 1 65 10 '3.7X10 2 9 1O 1.0)(10 1. 65 10 5. 2x10 6. 8X10 8. 7x10 Example 11 Thepasteurized egg whites of Example 1 were tested for any indication of analteration of the functional properties. Accordingly, 176 grams of theegg whites were mixed with a kitchen style mixer for seconds. The amountof foam thus generated was then measured. The quantity of foam producedis a measure of the degree of protein denaturation that may occur duringpasteuriza tion. The amounut of foam produced by the egg whites in 90seconds is inversely proportional to the amount of protein denaturedduring pasteurization. The volume of foam produced under theseconditions is reported as specific volume determined by dividing thetotal amount of foam generated in milliliters by weight of the eggwhites in grams. Thus, a specific volume of less than 3 indicates anexcess of denaturation of the egg whites that is undesirable. However,the egg whites treated as set forth above had a specific volume of over6. After the specific volume of the egg whites had been measured, thebaking performance thereof was measured by preparing angel food cakesfrom the pasteurized egg Whites. Thus, the 176 grams of egg whites werebeat for an additional two minutes with the kitchen style mixer.Thereafter, 2.45 grams of cream of tartar, 0.70 grams of salt, and 84.0grams of sugar were added. The mixture was then blended for anadditional two minutes. Then, a blend consisting of 42 grams of flourand 45 grams of sugar was folded into the whipped egg Whites. Theresulting batter was placed in six inch pans and baked for thirtyminutes at 355 F. After baking, the volume of the cakes were measured bystandard seed displacement techniques. The specific volumes weredetermined by dividing the weight of the cakes in grams into the totalvolume. A specific volume greater than 3 is indicative of acceptable eggwhite functional properties. In this instance, the specific volume was4.3. Any changes in opacity of the egg Whites due to pasteurization wasmeasured by visual observation. An increase in opacity or the formationof solid protein particles is indicative of protein denaturation. Theegg whites pasteurized in accordance with this invention was clear.

What is claimed is:

1. The process for pasteurizing egg whites comprising the steps of:

(a) adding an alkali polyphosphate in an amount from between about 0.2to about 2.0% by weight to said egg whites;

(b) adjusting the pH of said egg whites to between about 8.0 and about10.0 with an alkaline material;

(c) heating said egg whites to a pasteurization temperature betweenabout F. and less than F. for a sufficient length of time to pasteurizethe said egg whites.

2. The process as set forth in claim 1, wherein said alkalipolyphosphate can be represented by the formula:

wherein n can range between about 3 and 40 and wherein saidpolyphosphate is linear or cyclic and is coupled to H O or Na O.

3. The process as set forth in claim 2, wherein said polyphosphatealkali polyphosphate materials is selected from the group consisting ofsodium hexametaphosphate, sodium tetrapolyphosphate, sodiumtripolyphosphate, sodium hexapolyphosphate, sodium heptapolyphosphate,sodium octapolyphosphate, and mixture thereof.

4. The process as set forth in claim 1, wherein said alkali material isselected from the group consisting of sodium hydroxide, potassiumhydroxide, ammonium hydroxide, sodium phosphate, calcium hydroxide,sodium carbonate and mixtures thereof.

5. The process as set forth in claim 1, wherein said pasteurizationtemperature is held for a period of from 0.5 to 10 minutes.

6. The process as set forth in claim 1, wherein said alkalipolyphosphate material is represented by the formula:

wherein n is between 3 and 40 and is linear of cyclic and is coupled toH O or Na O, and is selected from the group consisting of sodiumhexametaphosphate, sodium tetrapolyphosphate, sodium tripolyphosphate,sodium hexapolyphosphate, sodium heptapolyphosphate, sodiumoctapolyphosphate, and mixtures thereof, and is present in an amountranging between 0.20 to about 2.0% by weight.

7. The process as set forth in claim 6, wherein said alkaline materialis selected from the group consisting of sodium hydroxide, potassiumhydroxide, ammonium hydroxide, sodium phosphate, calcium hydroxide,sodium carbonate, and mixtures thereof.

8. The process as set forth in claim 1, together with the additionalsteps of cooling said pasteurized egg whites and readjusting the pHthereof to the natural level with a food grade acid.

References Cited UNITED STATES PATENTS 3,364,037 1/1968 Mink 99-161NORMAN YUDKOFF, Primary Examiner H. H. BERNSTEIN, Assistant ExaminerU.S. Cl. X.R. 99161 P0495, UNITED STATES PATENT OFFICE (sla CERTIFICATE9F CORRECTION Patent No. 5,757,550 Dated June 5; 975

InuentoflQWillibald F. Kohl, John c. Sourby & Rudolph H. Ellinger It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby 'corrected as shown below:

Column line 11, "a stheir" should be as their line 54, "bacteria shouldbe bacterial Column 5, line 12, "sulfat-er" should be sulfate Column 5,Table, under "After 72 hours at 25C. 2

9.1L x 10 should read 9. x10 and "6.0 x 10 should read 6.6) x lo Column5, line 40, 'amounut" should be amount Signed' and sealed this 19th dayof November 1974.

(SEAL) Attest: A

McCOY M.- GIBSON JR. c. MARSHALL DANN Attestirig Officer 5 Commissionerof Patents

